'''编写递归函数求n!'''


def Factorial(x):
    if x < 0:
        print("error input num!!!")
        return -1
    if x == 0 or x == 1:
        return 1
    return x*Factorial(x-1)


n = int(input("请输入你想求的阶乘数："))
print("%d !的阶乘为:%d " %(n,Factorial(n)))
Factorial(n)    